Snap-action vane



April 12, 1955 J, w, WELSH 2,706,226

SNAP-ACTION VANE Filed Aug. 18. 1953 2 Sheets-Sheet 1 i 35 J z? 59, 30 Iav F|G.7 g A%RNEY April 1955 J. w. WEkSH 2,706,226

' SNAP-ACTION VANE Filed Aug. 18, 1953 2 Sheets-Sheet 2 2' ed 0 a /0 a e.5 41 3 v INVENTQR F|G.8 a

A RNEY United States Patent SNAP-ACTION VANE James W. Welsh, Summit, N.J., assignor to Signal-Stat gorl loration, Brooklyn, N. Y., acorporation of New Application August 18, 1953, Serial No. 374,977

7 Claims. (Cl. 200-122) This invention relates to snap action electricswitches and, more particularly, to a snap action flasher embodying anovel pilot lamp contact arrangement.

Flashers are commonly used in automotive signalling circuits toflashingly energize the signal lamps when the circuits therefor areselectively closed. To indicate the operation of the signal lamps, apilot or indicator lamp is usually mounted on the dash-board orinstrument panel of the vehicle. This pilot lamp is flashed whenever thesignal lamps are energized, either in synchronism with the signal lampsor in alternation therewith.

The usual flasher includes a high resistance wire or strip which, whencurrent flows therethrough, heats rapidly and expands. The wire isoperatively associated with a movable switch arm to hold this armagainst a first contact when the wire is cold and thus contracted. Asthe wire expands, the arm is spring biased to disengage such firstcontact and break the heating circuit for the wire. The latter thereuponcools and contracts to reengage the arm with such first contact and thusreclose the heating circuit for the high resistance wire to repeat theoperating cycle. In some flashers, when the high resistance wire expandsto disengage the arm from the first contact, the arm engages a secondcontact which may control another circuit.

To operate the pilot lamp, a magnetic switch or relay is associated witheither one of the two contacts, dependent upon whether synchronous oralternate operation of the pilot lamp is desired. This relay, whenenergized, closes a circuit for the pilot lamp. The flasher parametersare generally so selected that, if a signal lamp is inoperative, thecurrent load is insuflicient to operate the relay and the pilot lamp isnot energized. This apprises the vehicle operator of lamp trouble in thesignal circuit.

The present flasher arrangements, including pilot lamp relays, whilereliable in operation, are relatively complicated and frequently tooexpensive for many installations. Hence, there is a demand for a simple,reliable and inexpensive flasher pilot lamp device.

In my co-pending application, Serial No. 374,976, filed August 18, 1953,for Snap Action Device," I have shown and described a novel snap actionvane which may be incorporated in a snap action switch. This vane isprovided with an initial deformation along a right line extending acrossthe vane by thinning or deform ing the vane along this line in two ormore spaced sections of the line, these sections being spaced at theirinner ends from the center of the vane and also preferably spaced fromthe outer ends of the bent line. When such a vane is to be utilized in asnap action switch, suchas a flasher, the vane is bent about anotherline, at an angle to the line of initial deformation, by applying forceto the ends of such line. When such force is released, the vane snapsback to its initial position, the action closely resembling that of atoggle.

The vane is held in the new deformed position by attaching a highresistance wire or strip at each of its ends to the vane at the ends ofthe line of initial deformation. This high resistance wire or strip thusforcibly holds the vane in a distorted position bent about a lineangularly related to the line of initial deformation. When the highresistance wire has electric current passing therethrough, it heats andexpands. During the expansion of the wire, a point is reached at whichthe tension exerted by the wire is over-balanced by the kinetic energyof the vane stored therein by bending the latter from its 2,706,226Patented Apr. 12, 1955 initial condition. At this point, the vane snapsback to its initial condition.

As described in said co-pending application, the vane has a mountingmember secured thereto at a point in an elliptical line representing thedistribution of stresses adjacent the vane center due to the initialdeformation of the vane. This mounting member extends across the highresistance wire and carries a contact cooperative with a contact carriedby a high resistance wire. When the vane is in the deformed position, inwhich it is held by the contracted high resistance wire, these twocontacts are in engagement, so that current from a source of electricpower connected to a contact carried by the mounting member flows inparallel paths through the high resistance wire, through the vane, andthence to the other terminal of the current source. When the vane snapsback to its initial condition as a result of heating and expansion ofthe wire, the contacts separate and the high resistance wire then coolsand contracts. During such contraction, the force exerted by the wireoverbalances the force tending to maintain the vane in its initiallydeformed condition, and the resultant toggle action snaps the vane tothe deformed condition reengaging the contact carried by the resistancewire with the contact carried by the mounting member for the vane. Theelectrical circuit is thus reclosed and the cycle repeats.

In my co-pending application, Serial No. 374,918, filed August 18, 1953,for Snap Action Device, a flasher or electric switch arrangementembodying such a vane and mounting structure is provided in which thetwo contacts are held in full pressure engagement, or even underincreasing pressure, during the time the resistance wire is heating andexpanding and right up to the instant that the vane snaps back to itspre-set condition. Thus, there is no diminution or reduction of contactpressure during the initial part of the switch opening movement orcycle, and full pressure is maintained between the contacts until theyare snapped apart by the snap action of the vane in restoring itself toits present deformation.

More specifically, the switch parameters are so se lected that, when thecontacts are engaged, and up to the time that the snap action takesplace, the resistance wire is depressed at its center toward the vane,so that the center of the wire exerts a force component in the directionof the contact carried by the vane mounting means. By proper selectionof the switch parameters, this contact pressure effecting force may bemade to increase during the expansion of the resistance wire so that atleast full contact pressure is maintained up to the instant the snapaction of the vane occurs.

At such instant, the contacts are snapped apart, thus instantaneouslymoving the contacts from the full pressure engaged position to a widelyseparated circuit breaking position. Thereby, with such arrangement, apilot of the current flowing across the contacts versus time willessentially resemble a square wave and there will be practically noslope to the lines connecting the full current portion'of the curve tothe no current portion of the curve.

Due to the depression of the resistance wire and the consequent increasein the stress imposed on the vane, as described in such latterapplication, there is a very substantial displacement of the vanecorners, to which the resistance wire is secured, during snapping of thevane between the stress-deformed and initially preset, or restoredpositions. In accordance with the present invention, this relativelylarge magnitude movement of. such vane corners is utilized to provide anovel pilot lamp circuit controlling arrangement.

In the invention arrangement, a contact is secured to one of such vanecorners for movement therewith. This contact is operatively associatedwith a second contact fixed relative to the vane mounting member orbracket. As the vane snaps between its deformed and restored positions,when the flasher is connected to a source of electric potential, theselast mentioned contacts are alternatively engaged and disengaged.

The pilot lamp is connected to the relatively fixed contact. Thevane-carried contact is made live by virtue of the circuit connection tothe vane through its mounting member. Thus, the pilot lamp is flashedwhenever the flasher is energized. Preferably, the pilot lamp contactsare engaged when the vane is in the restored position and disengagedwhenever the vane is snapped to the deformed position by coolingcontraction of the resistance wire, so that the pilot lamp flashes insynchronism with the signal lamps. However, a reverse interaction of thecontacts may be equally well provided to obtain alternation of the pilotlamp and signal lamp flashing.

Due to the division of the current in two parallel paths through theresistance wire, in the event a signal lamp is inoperative the resultantreduced current flow will be insuflicient to heat the wire sufficientlyto expand to the degree allowing snapping of the vane to the restoredposition. Thus, either steady burning or non-illumination of the pilotlamp will indicate a defective signal lamp.

For an understanding of the invention principles, refer ence is made tothe following description of a typical embodiment thereof as illustratedin the accompanying drawrngs.

In the drawings:

Fig. 1 is a perspective view of a snap action vane and mounting memberused in the invention flasher;

Fig. 2 is an elevation view, partly in section of the invention flasher;

Fig. 3 is an elevation view of the flasher at right angles to the viewof Fig. 2;

Figs. 4 through 7 are diagrams illustrating operating positions of theflasher;

Figs. 8a through 8h are graphical diagrams of the snap action of theflasher vane;

Fig. 9 is a partial plan view illustrating a modified contactconstruction; and

Fig. 10 is an elevation view on the line 1010 of Fig. 9.

Referring to Fig. 1, which is substantially identical with Fig. 1 of mysaid co-pending application, Serial No. 374,918, a snap action vane 10is illustrated which is identical with that shown and described in saidco-pending application. Vane 10 is preferably made of relatively thinspring metal, with consideration being given to its spring factor,stiffness, temperature coefficient, and the like, in accordance with thedesired rate of operation of the snap action.

To provide an initial set to vane 10 and to give the same some depth sothat it will resemble a beam in its action, the vane 10, which is shownas a substantially rectangular vane, is deformed or thinned along adiagonal interconnecting corners 11 and 12. This vane deformation ispreferably effected by lineally embossing the vane along the line 11--12in two elongated spaced portions or bosses 15. It will be noted that thebosses have their inner ends disposed substantially equal distances fromthe center of vane 10 so that the center area of the vane is leftunmarred. As explained in said copending application Ser. No. 374,976,this greatly prolongs the life of vane 10 by removing the stressconcentration from the center to a pair of points on bosses 15. If thedeformation lines 11--12 were continuous through the vane center area,the flattening of the vane at the center during repeated cycles wouldeventually cause fatigue of the vane at the center and reduce the amountof force required to snap the vane between the illustrated position andanother deformed position. Due to the bosses 15, 15, the sections 13 and14 of the vane on either side of line 11-12 bend upwardly so that thevane assumes the form of a shallow vee (V) having its apex on line 1112.When vane bending forces are applied to the end of lines 1112, and thevalue of these forces equals or over-balances the inherent tendency ofthe vane to stay in its preset condition, the vane snaps into a new bentor deformed position, forming another shallow vee (V) along the otherdiagonal 16--17. When the forces at points 11 and 12 are decreased to apoint where they are overbalanced by the kinetic energy stored in vane10 due to such distorting force, the vane snaps back to a position bentalong the lines 11-42.

Photographs, taken with polarized light, of a transparent vane formed inthis manner show lines of force in the unmarred center area of the vanewhich comprise elliptical bands having radii centered on the vanecenter. If the vane is secured or supported at a point on one of theseelliptical stress loci, the stress points on the vane during applicationof bending force at corners 11 and 12 occur within the lengths of bosses15. Thus, the stresses are removed from the center area and distributedbetween two points spaced from the center. This greatly prolongs theperiod before fatigue takes place in the stressed section of the vane.As described in said co-pending application Ser. No. 374,976, advantageis taken of this fact by supporting the .vane by securing the latter, ata point of one of such elliptical lines of force, to a relatively rigidelectrically conductive metal mounting member 20. The point ofattachment of the mounting member to the vane acts as a pivot point forthe vane during its snap action and is preferably spaced laterally ofthe initial bend line 1112.

When the vane is used to form a snap action switch, the bending stressesmay be conveniently applied to points 11 and 12 by means of a highresistance wire or strip 30 secured to these corners of the vane. Forthis purpose, the points 11 and 12 are bent downwardly as illustrated inFig. l, and the ends of wire or strip 30 are secured thereto at 31 and32, while the vane is bent along the line 1617, so that the wire in itscold or contracted position holds the vane deformed into a vee (V)having its apex along line 16-17. If wire 30 has electric current passedtherethrough, it expands and, as the wire force is overbalanced by therestoring kinetic energy built up in vane 10, the vane snaps back to itsinitially bent condition along the line 11 12.

An arrangement for utilizing this action is illustrated in Figs. 2 and3, which show the invention snap action switch. The center section 21 ofmounting member has a band 23 of insulation wrapped thereon and a band24 of conductive metal is wrapped around band 23. Band 24 carries acontact point 25 at the intersection of mounting member 20 and wire 30.The wire has a contact point secured to its mid-section for cooperationwith contact 25.

The free end of mounting member 20 is secured to a dielectric base as bya rivet connecting the outer end 26 of member 20 to a prong or terminal42 on base 40. Another prong or terminal 33 is connected by rivet 34 toa conductive strip 44 connected to band 24.

In accordance with the invention, base 40 has a third terminal or prong36 secured by rivet 37 to a stepped contact aligned beneath a corner 11or 12 of vane 10. Contact 55 is thus fixed relative to base 40 andbracket 20. Cooperable with fixed contact 55 is a movable contactsecured to one of the corners 11, 12 of vane 10. Contact 60 is L-shapedand has a leg 61 projecting laterally between the olfset spring end 56of contact 55 and base 40. In the illustrated stress-deformed positionof vane 10, arm or leg 61 is spaced from end 56 of contact 55, so thatcontacts 55, 60 are separated or open.

Referring to Fig. 4, a grounded battery 44 is connected, through asignal lamp control switch 45, to terminal 33, and thus throughconductor 43 to band 24 and contact 25. A conductor 46 connects terminal42, and thus vane 10 and bracket 20, to parallel and grounded signallamps SL-l and SL-2. A conductor 47 connects terminal 36, and thusrelatively fixed contact 55, to grounded pilot lamp PL.

Referring more particularly to Figs. 2 and 4, the switch parameters areso selected that, in the contracted or cooled condition of wire 30,contacts 25 and 35 are engaged and the relation of parts is such thatthe center part of wire 30, carrying contact 35, is forced inwardlytoward vane 10. The wire thus assumes a shallow vee (V) as is shown inFig. 2, and the tension of wire 30 thus increases the force with whichcontacts 25 and and 35 are held engaged.

When switch 45 is closed, current flows from battery 44 through switch45, conductor 43, band 24 and contact points 25 into contact point 35 atthe midpoint of wire 30. At this midpoint, the current branches throughboth halves of wire 30, in parallel, and flows into vane 10 at points 31and 32. The current flows through vane 10 into mounting member orbracket 20, and thus through rivet 41 into prong 42 and throughconductor 46, resistance 47 and switch 48 to the other side of thecurrent source. The current flowing through wire 30 causes the latter torapidly heat and expand, this wire preferably being Nichrome wire. Aswire 30 expands and thus lengthens, the force exerted by the wire isfinally overbalanced by the kinetic energy stored in vane 10, and thelatter snaps to its initial or restored position. This pulls wire 30downwardly relatively to bracket 20, and snaps contacts 25 and 35 apartto break the electrical circuit. The wire 30 then cools and contracts.As the force exerted by the contracting wire overbalances the forcetending to maintain vane in its restored position, the vane again snapsto a position bent along line 16-17 wherein wire 30 snaps toward bracket20 to reengage contacts and 35. The cycle then repeats.

The initial relation of parts is shown diagramatically in Fig. 4, whichcorresponds to the position of the switch or flasher shown in Fig. 2. Itshould be noted that the connection of battery 44 to prong or terminal33 is exemplary only, and that the connections of terminals 33 and 42could be reversed with battery 33 connected to terminal 42 and lampsSL-l, SL-2 to terminal 33. This reversal will result in a slightlydifferent operation of pilot lamp PL as will be explained in connectionwith Fig. 7. With the parts as shown in Fig. 4, and with switch 45closed, lamps SL-l and SL2 have a potential applied thereacross. Due tothe bending of vane 10 about the line 16-17, corners 11, 12 of the vaneare depressed so that contacts 55 and 60 are disengaged. Thus, pilotlamp PL is not lit. Wire is heating and expanding, and thus corners 11,12 are moving upwardly.

Should only one signal lamp SL-l or SL2 be operative, the currentthrough wire 30 will be insuflicient to heat and expand the wire anamount sufficient for the stored energy in vane 10 to snap the vane toits restored position. By proper initial spacing of contacts 55 and 60,these contacts can be made to remain out of engagement during suchpartial heating of wire 30 and the resultant partial movement of vane 10toward the restored position. This condition is illustrated in Fig. 5,wherein vane 10 has moved only partially toward the restored position,due to reduced current flow in wire 30 as a result of one signal lampbeing inoperative. Continued failure of pilot lamp PL to light indicatesa defective condition of the signal lamp circuit.

However, if both signal lamps are operative, wire 30 continues to expandand vane 10 continues to flatten, thus moving corners 11, 12 upwardlysufficiently to engage contacts 55, 60 to energize pilot lamp PL. Thisposition is shown in Fig. 6.

As the wire 30 continues to heat and expand, the energy of vane 10over-balances the stress imposed by wire 30 and the vane snaps to therestored position. This separates contacts 25 and to open the signallamp and wire 30 heating circuit. While contacts 55, 60 remain engaged,due to the full upward movement of corners 11, 12, lamp PL isdeenergized due to opening of contacts Should the circuit connections toterminals 33 and 42 be reversed from those of Fig. 4, however, lamp PLwould remain energized due to battery potential being applied directlyto vane 10 through bracket 20.

In either case, contacts 55, 60 remain engaged in the restored positionof vane 10. To accommodate the relatively large magnitude movement ofcorners 11, 12 and remain in contact over a long period, either or bothcontacts 55, 60 are made resilient. In Fig. 7, wire 30 is starting tocool and contract and, as the stress exerted thereby over-balances theresistance of vane 10, the vane snaps back to the position of Figs. 2and 4. The cycle then repeats.

Referring now to Figs. 8a through 8h, the action of the invention switchmaintaining full contact pressure until the circuit break point isreached will be described as graphically illustrated. Before proceedingto this description, it should be mentioned that the mounting of contact35 at the mid-point of wire 30 has several important advantages. In thefirst place, the resistance is decreased due to the parallel circuitsthrough wire 30. This enables the use of a wire rather than a ribbon forthe high resistance element which facilitates the proper expansion. Inthe second place, this contact position is utilized to increase thepressure in wire 30, thus assuring a faster snap action at the end of acycle. A third ad vantage is that this mounting of contact 35 in effectprovides lever arms between the center of the vane and the vane mountingpoint which comprise springs storing kinetic energy.

The relatively fixed mounting point of member 20 is illustrated by theline F carrying the contact point 25. The lines a through e arereference lines graphically illustrating the lengthening and contractingof wire .30. The lines OX are scale lines indicating relative verticalmove- 6 ment of the ends of wire 30 relative to the fixed reference lineF. The angle B is proportional to the vane deflection. This angle isalso indicative of the contact pressure.

As shown, in the contracted position of wire 30 illustrated in Fig. 8athe wire is bent into a shallow inverted vee (V) so that the force ofthe wire tends to increase the pressure between contacts 25 and 35, thewire 30 acting as a pressure increasing spring. In Fig. 8a, wire 30 iscool and is just about to be heated. The vane apex is in an elevatedcondition illustrated by point M due to the mechanical advantageprovided when vane 10 is secured at a stress loci point to bracket 20.The vane center is also raised due to the stress imparted thereto by theupward bending of wire 30 to increase the contact pressure. Wire 30 iscontracted to its smallest length as indicated by its ends lying onlines a-a. As the center of vane 10 is high, a small force in the wirewill hold the vane due to the relatively large angle B of the togglejoint arrangement.

As the wire starts to heat, the parts assume the position of Fig. 8b.Wire 30 has increased in length to lines b-b, and the center section ofvane 10 is lowered to the line N due to flattening of the vane adjacentto its center section. Wire 30 upon elongating tends to raise its endsbut its center, being higher than its ends, as previously explained, islower in Fig. 8b than in Fig. 8a, thus giving an overall lowering of thevane ends from line 4 to a position between lines 4 and 5. The loweringof the vane ends increases angle B, thus increasing the contactpressure.

In Fig. 8c wire 30 has lengthened so that its ends are on the lines 0-0.The center section of vane 10 has moved down to line 0 and isapproaching a flat condition so that its downward movement diminishes.However, the stored energy in the vane decreases, thus providing a newangular relationship. The pressure on contacts 25 and 35 remainssubstantially the same as in Fig. 8b. The wire relationship also remainsabout the same as in Fig. 8b. Angle B becomes smaller so that thetension in wire 30 increases.

In Fig. 8d, the wire has lengthened so that its ends are at the linesd-d, vane 20 is approaching a flat condition, and wire 30 is under greatstress. The vane center has lowered slightly. The contact pressure hasincreased due to the decrease in angle B and the vane is about to snapto its restored condition.

Fig. 8c shows the relation of parts immediately after such snapping ofthe vane to change the apex of the vee (V) from line 16-17 to line11-12. The relationship of wire 30 to the mounting 20 has changed, dueto the snapping of vane 10, thus snapping open contacts 25 and 35 tobreak the circuit. The wire is essentially the same length as in Fig. 8dand angle B is quite small.

In Fig. 8f, wire 30 is contracting to build up pressure in the vane andincrease the angle B. The vane angle is decreasing and the resultant isa build-up in pressure in wire 30, which has moved slightly in an upwarddirection. However, as the vane center is moving more than the wire, theresultant movement of wire 30 is toward line F representing bracket 20.

In Fig. 8g, wire 30 is still contracting but is moving towards bracket20 due to the diminishing of the upward movement of the vane center asit approaches the flat condition. The stress in wire 30 has increasedand the movement of the parts begins to accelerate. Angle B isincreasing and thus building up kinetic energy in vane 10.

Fig. 8h illustrates a position where wire 30 has contracted even furtherthan the position shown in Fig. 8g and vane 10 is about to snap to abend along lines 16-17 to assume the position diagrammaticallyillustrated in section 6.

In the modified arrangement of Figs. 9 and 10, the vane carried pilotlamp contact 60' is a short straight bar welded to vane 10 adjacent acorner 11 to project from the vane. Contact 60' is cooperable with a Z-shaped bar contact 55' welded to rivet 37 of terminal 36. Thisconstruction is more practical from a commercial standpoint, but thecontacts 55' and 60' interact in the same manner as contacts 55, 60.

The invention thus takes advantage of the snap action movement of thevane 10 to provide a record and simplified pilot lamp energizingarrangement for flashers. This arrangement fulfills all the usualrequirements for pilot lamp operators, including the circuit defectindicating function, in an inexpensive and simple construction.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the inventionsprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. A snap action electric switch comprising, in combination, adielectric base; a substantially fiat vane of electrically conductiveresilient material having a substantially linear preset deformationextending thereacross, said deformation being interrupted intermediateits ends at points substantially equi-distant from the vane center toleave the central area of the vane free of preset deformation; a firstterminal on said base; an elongated electrically conductive bracketsecured at one end to said vane at a vane mounting point spacedlaterally from said deformation, and secured at its other end to saidfirst terminal; means operable to alternately apply and release vanebending stresses at points adjacent the outer ends of said deformationto effect snapping of the vane between a stress-deformed position inwhich the vane is bent along a line substantially perpendicular to saiddeformation and a preset restored position in which the vane is bentalong said deformation; the free portion of the vane, during suchsnapping action, pivoting about such mounting point, and the ends ofsaid deformation moving substantially relative to said base during thesnapping action of the vane; a first contact on said vane adjacent anend of said deformation; a second terminal on said base; and a secondcontact secured to said second terminal and disposed in the path ofmovement of said first contact for engagement with the latter in one ofsaid vane positions and disengagement therefrom in the other of saidvane positions.

2. A snap action electric switch comprising, in combination, adielectric base; a substantially flat and rectangular vane ofelectrically conductive resilient material having a substantially linearpreset deformation extending thereacross along a diagonal, saiddeformation being interrupted intermediate its ends at pointssubstantially equi-distant from the vane center to leave the centralarea of the vane free of preset deformation; a first terminal on saidbase; an elongated electrically conductive bracket secured at one end tosaid vane at a vane mounting point spaced laterally from saiddeformation, and secured at its other end to said first terminal; meansoperable to alternately apply and release vane bending stresses atpoints adjacent the outer ends of said deformation to effect snapping ofthe vane between a stress deformed position in which the vane is bentalong the other diagonal of the vane and a preset restored position v inwhich the vane is bent along said deformation; the free portion of thevane, during such snapping action, pivoting about such mounting point,and the ends of said deformation moving substantially relative to saidbase during the snapping action of the vane; a first contact on saidvane adjacent an end of said deformation; a second terminal on saidbase; and a second contact secured to said second terminal and disposedin the path of movement of said first contact for engagement with thelatter in one of said vane positions and disengagement therefrom in theother of said vane positions.

3. A snap action electric switch comprising, in combination, adielectric base; a substantially flat vane of electrically conductiveresilient material having a substantially linear preset deformationextending thereacross, said deformation being interrupted intermediateits ends at points substantially equi-distant from the vane center toleave the central area of the vane free of preset deformation; a firstterminal on said base; an elongated electrically conductive bracketsecured at one end to said vane at a vane mounting point spacedlaterally from said deformation, and secured at its other end to saidfirst terminal; means operable to alternately apply and release vanebending stresses at points adjacent the outer ends of said deformationto effect snapping of the vane between a stress-deformed position inwhich the vane is bent along a line substantially perpendicular to saiddeformation and a preset restored position in which the vane is bentalong said deformation; the free portion of the vane, during suchsnapping action, pivoting about such mounting point, and the ends ofsaid deformation moving substantially relative to said base during thesnapping action of the vane; a first contact on said vane adjacent anend of said deformation; a second terminal on said base; and a secondcontact secured to said second terminal and disposed in the path ofmovement of said first contact for engagement with the latter in therestored position of the vane and disengagement therefrom in thestress-deformed position of the vane.

4. A snap action electric switch comprising, in combination, adielectric base; a substantially flat and rectangular vane ofelectrically conductive resilient material having a substantially linearpreset deformation extendng thereacross along a diagonal, saiddeformation being interrupted intermediate its ends at pointssubstantially equi-distant from the vane center to leave the centralarea of the vane free of preset deformation; a first terminal on saidbase; an elongated electrically conductive bracket secured at one end tosaid vane at a vane mounting point spaced laterally from saiddeformation, and secured at its other end to said first terminal; meansoperable to alternately apply and release vane bending stresses atpoints adjacent the outer ends of said deformation to effect snapping ofthe vane between a stressdeformed position in which the vane is bentalong the other diagonal of the vane and a preset restored position inwhich the vane is bent along said deformation; the free portion of thevane, during such snapping action, pivoting about such mounting point,and the ends of said deformation moving substantially relative to saidbase during the snapping action of the vane; a first contact on saidvane adjacent an end of said deformation; a second terminal on saidbase; and a second contact secured to said second terminal and disposedin the path of movement of said first contact for engagement with thelatter in the restored position of the vane and disengagement therefromin the stress-deformed position of the vane.

5. A snap action electric switch comprising, in combination, adielectric base; a substantially flat and rectangular vane ofelectrically conductive resilient material having a substantially linearpreset deformation extending thereacross along a diagonal, saiddeformation being interrupted intermediate its ends at pointssubstantially equi-distant from the vane center to leave the centralarea of the vane free of preset deformation and with curvilinear stressconcentration loci concentric with the vane center; a first terminal onsaid base; an elongated electrically conductive bracket secured at oneend to said vane at a vane mounting point on one of said loci, andsecured at its other end to said first terminal; means operable toalternately apply and release vane bending stresses at points adjacentthe outer ends of said deformation to effect snapping of the vanebetween a stress-deformed position in which the vane is bent along theother diagonal of the vane and a preset restored position in which thevane is bent along said deformation; the free portion of the vane,during such snapping action, pivot: ing about such mounting point, andthe ends of said deformation moving substantially relative to said baseduring the snapping action of the vane; a first contact on said vaneadjacent an end of said deformation; a second terminal on said base; anda second contact secured to said second terminal and disposed in thepath of movement of said first contact for engagement with the latter inthe restored position of the vane and disengagement therefrom in thestress-deformed position of the vane.

6. A snap action electric switch comprising, in combination, adielectric base; a substantially fiat and rectangular vane ofelectrically conductive resilient material having a substantially linearpreset deformation extending thereacross, said deformation beinginterrupted intermediate its ends at points substantially equidistantfrom the vane center to leave the central area of the vane free ofpreset deformation and with curvilinear stress concentration lociconcentric with the vane center; a first terminal on said base; anelongated electrically conductive bracket secured at one end to saidvane at a vane mounting point on one of said loci, and secured at itsother end to said first terminal; an expansible high resistance electricconductor secured at each end to said vane adjacent the outer ends ofsaid deformation under tension and parallel to said deformation, to bendsaid vane to a stress-deformed position in which the vane is bent alongthe other diagonal of the vane; said vane, upon a predeterminedexpansion of said conductor, snapping to a preset restored position inwhich the vane is bent along said deformation; the free portion of thevane, during such snapping action, pivoting about such mounting point,and the ends of said deformation moving substantially relative to saidbase during the snapping action of the vane; a first contact on saidvane adjacent an end of said deformation; a second terminal on saidbase; a second contact secured to said second terminal and disposed inthe path of movement of said first contact for engagement with thelatter in one of said vane positions and disengagement therefrom in theother of said vane positions, said bracket extending across the centralarea of said vane outwardly of said conductor; a third terminal on saidbase; a third contact mounted in insulated relation on said bracket inalignment with said conductor and connected to said third terminal; anda fourth contact secured to said conductor intermediate the conductorends and engaged with said third contact when said conductor iscontracted to bend said vane to such stressdeformed position; saidconductor, in the restored position of said vane, lying in juxtapositionto said vane and spaced sutiiciently from said bracket to fullydisengage said third and fourth contacts.

7. A snap action electric switch comprising, in combination, adielectric base; a substantially flat and rectangular vane ofelectrically conductive resilient material having a substantially linearpreset deformation extending thereacross, said deformation beinginterrupted intermediate its ends at points substantially equidistantfrom the vane center to leave the central area of the vane free ofpreset deformation and with curvilinear stress concentration lociconcentric with the vane center; a. first terminal on said base; anelongated electrically conductive bracket secured at one end to saidvane at a vane mounting point on one of said loci, and secured at itsother end to said first terminal; an expansible high resistance electricconductor secured at each end to said vane adjacent the outer ends ofsaid deformation under tension and parallel to said deformation, to bendsaid vane to a stress-deformed position in which the vane is bent alongthe other diagonal of the vane; said vane, upon a predeterminedexpansion of said conductor, snapping to a preset restored position inwhich the vane is bent along said deformation; the tree portion of thevane, during such snapping action, pivoting about such mounting point,and the ends of said deformation moving substantially relative to saidbase during the snapping action of the vane; a first contact on saidvane adjacent an end of said deformation; a second terminal on saidbase; a second contact secured to said second terminal and disposed inthe path of movement of said fist contact for engagement with the latterin one of said vane positions and disengagement therefrom in the otherof said vane positions, said bracket extending across the central areaof said vane outwardly of said conductor; a third terminal on said base;a third contact mounted in insulated relation on said bracket inalignment with said conductor and connected to said third terminal; afourth contact secured to substantially the mid-point of said conductorand engaged with said third contact when said conductor is contracted tobend said vane to such stress-deformed position; said conductor, in therestored position of said vane, lying in juxtaposition to said vane andspaced sufficiently from said bracket to fully disengage said third andfourth contacts.

References Cited in the file of this patent UNITED STATES PATENTS2,133,309 Schmidinger Oct. 18, 1938 2,194,999 Clark Mar. 26, 19402,274,399 Cook Feb. 24, 1942

